When the Tree Rings Talk, Climate Scientists Get Nervous

Perhaps it was just a coincidence that a new study on the long term patterns of global temperature change was released as much of the US sizzled under scorching temperatures that triggered high winds and storms that knocked down trees and cut power for more than a week.

But if climate change activists hoped for a new batch of true believers to emerge from the week from hell without air conditioning, there were probably glad to have the power cut so we all could not read the new study results first hand as we surfed the web.

“Solar insolation changes, resulting from long-term oscillations of orbital configurations1, are an important driver of Holocene climate2, 3. The forcing is substantial over the past 2,000 years, up to four times as large as the 1.6 W m−2 net anthropogenic forcing since 1750 (ref. 4), but the trend varies considerably over time, space and with season5. Using numerous high-latitude proxy records, slow orbital changes have recently been shown6 to gradually force boreal summer temperature cooling over the common era. Here, we present new evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (−0.31 °C per 1,000 years, ±0.03 °C) than previously reported, and demonstrate that this signature is missing in published tree-ring proxy records. The long-term trend now revealed in maximum latewood density data is in line with coupled general circulation models7, 8 indicating albedo-driven feedback mechanisms and substantial summer cooling over the past two millennia in northern boreal and Arctic latitudes. These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times.”

Did you get it?

OK here is my cheat sheet on the headlines from this study.

Incontrovertible Evidence of Man-made Climate Change Isn’t. The climate scientists including those involved in the IPCC research team miscalculated the data suggesting that the climate is warming faster than historic averages.

A Contrary Inconvenient Truth is Revealed. The IPCC conclusion that warming is caused by man-made forces appears to be inaccurate. It was hotter 2000 years ago than now.

The Historic Long Term Temperature Trend is Cooling not Warming. The Tree Ring study suggests current warming is less serious than the Romans faced with a more accurate study of the tree ring data suggesting the overall temperature trend is actually down by 0.3°C per millennium.

The Earth revolves Around the Sun. The Tree Ring Study scientists suggest a better explanation for the temperature changes and the gradual long-term cooling resulting is due to shifts in the position of the Sun and the Earth’s orbit around it. Professor Esper says: “This figure we calculated may not seem particularly significant. However, it is also not negligible when compared to global warming, which up to now has been less than 1°C. Our results suggest that the large-scale climate reconstruction shown by the Intergovernmental Panel on Climate Change (IPCC) likely underestimate this long-term cooling trend over the past few millennia.”

Professor Lu, at Oxford University in England when this work was done but now is a professor at Syracuse University, and a team of climate scientists from around the world studied temperature changes over time in Antarctica. They found the same pattern as the IPCC said only happened in Europe. “We showed that the Northern European climate events influenced climate conditions in Antarctica.” Thus the Antarctic study ikaite record suggests that temperature conditions found in the Medieval Warm Period and Little Ice Age in Europe were also confirmed to have happened on the Antarctic Peninsula but then cooled suggesting that the earth has experienced patterns of warming and cooling entirely unrelated to man-made activity. Lu’s work is published in the journal Earth and Planetary Science Letters.